Srtp: Turn off unused-but-set-variable warning
Srtp: Turn off unused-but-set-variable warning

For build-system CFLAGS clean-up, turn off warning.

Change-Id: Ia678d0668142d34b7c512d48347a71648f01ac9d

geekboxzone/mmallow_external_srtp,geekboxzone/mmallow_external_srtp,geekboxzone/mmallow_external_srtp